Ms Pelosi said the US Congress will not support a free trade agreement with the United Kingdom if the Government persists with “deeply concerning” plans to “unilaterally discard” the protocol.
In a strongly-worded intervention, Ms Pelosi urged the UK and the EU to continue negotiations on the post-Brexit trade arrangements to, in her view, uphold peace in the Province.
The congresswoman said in a statement: “The Good Friday Accords are the bedrock of peace in Northern Ireland and a beacon of hope for the entire world.
“Ensuring there remains no physical border between the Irish Republic and Northern Ireland is absolutely necessary for upholding this landmark agreement, which has transformed Northern Ireland.”
The comments from Ms Pelosi are a reminder of the ongoing interest in Northern Ireland in Washington, amid political instability following the Assembly election.
The DUP leader said: “I noted that Speaker Pelosi talked about the lack of a bipartisan approach or agreement on what the UK government are doing.
“The problem for Speaker Pelosi is that there is not bipartisan or cross-community support for the protocol in Northern Ireland, it is undermining the Belfast/Good Friday Agreement, it is undermining the political institutions that were established under that agreement, it undermines the principle of consent.
“You cannot have powersharing without consensus in Northern Ireland so the bipartisanship or the consensus that is required is not won in the US congress, it’s won in the Northern Ireland Assembly and I would urge Speaker Pelosi to understand that because I think that her contributions are entirely unhelpful, offer no solution, offer no help and merely repeat a mantra that frankly is hopelessly out of date.”
UUP leader Doug Beattie described the comments from Ms Pelosi as “not just deeply regrettable and misinformed ... but completely wrong”.
“Nancy Pelosi’s comments will only lead to a hardening of positions rather than easing a pathway to solutions which is what all politicians should be concentrating on,” he said.
Mr Beattie continued: “The Protocol does not protect the Belfast Agreement, it does the exact opposite by undermining East-West relationships; an important strand of the Belfast Agreement.”
The TUV was also critical of Ms Pelosi, adding “the interference of foreign figures in what are internal UK matters is unwelcome and inappropriate”.